As shown in a conventional vending machine, an apparatus operated by coins has detected the quality, the thickness and the diameter of the inserted coins to detect the kind of inserted coins, that is, to discriminate whether the inserted coin is a counterfeit one or a normal one. However, it has been inefficient to detect correctly the kind of coins because of various elements, that is, changes of circumference, environment such as humidity, temperature and approximation of metal object, influencing selection of the coin detection circuit.
Also, the conventional apparatus does not detect whether the coin is passed entirely through an insertion path but detects whether the coin is required or repaid by controlling a gate. Accordingly, although the coin is clogged and not able to pass through the coin insertion path due to insertion of a crushed coin or a counterfeit one, the apparatus is operated continuously. For this reason, when other users insert coins without knowing about the clogging of the insertion path, they suffer losses with reluctance.
On the other hand, methods for detecting coins are disclosed in U.S. Pat. No. 4,436,196 and Japanese laid-open Patent No. Sho 56-63685 respectively to discriminate the kind of coins, in which the automatic compensation of parameters is produced and the compensated signal is produced to discriminate the coins according to the material quality, the thickness, and the diameter of the coins and in which the kind of coin is discriminated by comparing the time required for each checking element.
The method disclosed in the U.S. Pat. No. 4,436,196 is one for detecting the coins in which a flux change occurs when the coin passes between the coil runway which has been associated with a coil set comprising a transmit coil and a receive coil and the coils of the coil set, and the signals derived from the received coil are combined to produce a compensated signal corrected for environmental changes, thereafter the compensated signals and the stored coil parameters and compared with each other.
In this method, firstly the first coil set selects coins to generate the information about the coin in the device using a coin or a token and then the second coil automatically sets parameters according to the environmental change and apparatus by providing a reference signal which compensates for temperature and drift. Detecting the sum of coins is performed by comparing the compensated signal with the stored coin parameter to detect the coin by the quality, the thickness and the diameter of the coins. Alternatively, the second method disclosed in Japanese laid-open Patent No. Sho 56-63685 is a method in which the first to the third checking elements are arranged according to the coin runway such that one end of the coin for discrimination is located on the third checking element while the other end thereof is located between the first checking element and the second one. The ratio between the time required for the back end of the coin to pass the third checking element after the back end of the coin has passed the first checking element and the time required until the back end of the coin has passed the second checking element after the back end of the coin has passed the first checking element is calculated.
Thereafter with the calculated value, the kind of coins are detected according to the compared result which has been obtained by comparing the above value with the memorized acceptable values. According to the aforementioned method, the kind of coin is detected according to the ratio of time required for the coin to pass the state of predetermined checking by using contactless type checking elements which are located in relation to a predetermined place so that it is not necessary to have high accuracy for installation of checking elements and checking elements are discriminated into three types regardless of the kind of coins.
The methods for detecting coins, in accordance with the U.S. and Japanese patent, detect only whether the inserted coin is a normal or counterfeit one by detecting the quality, the thickness and the diameter of the coin, and can not detect whether or not the insertion coin passes completely through the insertion path, and detect only whether the coin is inserted correctly or returned through the control of the gate. Accordingly, it is critical that the unit operates continuously even when the crushed or counterfeit coins are inserted but do not pass through the insertion path and cause the path to clog up.